Just when you think Big Dance Numbers have gone the way of the passenger pigeon, along came Lin-Manuel Miranda’s In the Heights, the Academy Award-nominated (and commendable) new West Side Story, and the disappointing, but innovatively cast, Cyrano, all of which displayed innovative dance sequences. (I still get dizzy thinking of the dance/fight sequence in West Side Story, in which it seemed Tony or Riff—or both—would fall through the broken pier into the Hudson.)

Film historian Max Alvarez recently hosted a program on “filming the dance,” and how that has changed over the decades. When films acquired sound, the studios made a lot of quickie musicals to take advantage of the new technology, and persuade audiences they were the new thing. These films weren’t always good. But the studios had made a big investment in converting movie houses and equipment to accommodate sound, and they were determined to recoup. As a result, in 1929, the studios produced 50 musicals and in 1930, an astonishing 78! You’ll recall that the Gene Kelly movie, Singin’ in the Rain, is about the difficulties of the conversion to sound, and Max says it’s pretty accurate. (That movie is having its 70^th anniversary this year.)

After the initial blitz of so-so products, movie makers became more discriminating about the form. In Hollywood’s “Golden Age,” the studio system was in full sway, and not only actors and directors, but songwriters and choreographers also had studio contracts. This made musicals economical to produce. Of course, early producers remained a little nervous about musicals. For one of his films, Darryl Zanuck put all the musical numbers at the end, so he could lop them off if audiences didn’t respond. Finally, the success of 42^nd Street (1933) did a lot to assuage their nerves. Treat yourself with this Busby Berkeley number from the show. Glorious! Thrilling! Unforgettable!

For a time, the orchestra played, the singers sang, and dancers danced. Big soundproofed boxes had to be built around the cameras to dampen their noise. Today, none of that happens simultaneously, of course, as songs and music are recorded separately. Photographing dance sequences is almost a lost art, Alvarez says, because directors don’t trust audiences to follow the action, so they do a lot of quick cuts. It’s lively, but all the editing sacrifices something. Gene Kelly maintained that the use of a lot of fast cutting was simply to camouflage bad choreography. Even the sound of “those dancing feet” is added in post-production. There aren’t any taps on their shoes. Sorry.